The Fredericton Fire Department is cautioning people about the use of cup holder ashtrays after several significant fires resulted from their use.

The ashtrays are made of a type of plastic and look like a cup, but with a hole in the top through which cigarette butts can be dropped.

Cup holder ashtray

The Fredericton Fire Department is concerned about fire starting as a result of improper use of cup holder ashtrays like this. (Fredericton Fire Department)

There is supposed to be some water in the cup. But firefighters have found problems result if adequate water is not in the cup.

"Recently we have had several fires involving these cup holder ashtrays," cautions the department on its Facebook page.

"They are sold as a type of fire resistance plastic, however if not properly emptied and a water level maintained in the bottom they can ignite.

"We recommend a sturdy glass or ceramic type ashtray be used at all times."